This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Hypothesis: IV remifentanil stimulates spinal COX activity, leading to increased CSF PGE2 concentrations and areas of capsaicin-induced mechanical hypersensitivity after remifentanil infusion, and these effects will be blocked by intrathecal ketorolac Synopsis: Areas of mechanical hyperalgesia and allodynia will be established by topical capsaicin + intermittent heat in healthy volunteers, who will be randomized to receive intrathecal saline or ketorolac during remifentanil infusion, with primary outcome measure area of hyperalgesia and secondary outcome measure CSF PGE2 concentration after stopping remifentanil.